1. Field of the Invention
The present invention relates to an air conditioning unit for a vehicle and an air conditioning system employing the air conditioning unit.
2. Description of Related Art
Recent vehicles are equipped with an air conditioning system component in an instrument panel in front of a front seat. The instrument panel is usually provided with various electronic instruments of the vehicle, and such instruments restrict the space for the air conditioning system in the instrument panel.
Conventionally, an air conditioning system in an instrument panel of a vehicle is laid out by placing an air conditioning unit having an evaporator and a heater core at a widthwise center of the vehicle and by arranging a fan unit on the front passenger seat side of the air conditioning unit (for example, FIG. 26 of Japanese Unexamined Patent Application Publication No. Hei-9-123748). This layout concentrates the evaporator and heater core at the widthwise center of the vehicle to secure space in the instrument panel. This is called a centralized layout.
To meet a recent requirement for decreasing noise in vehicle cabins (passenger compartment), there is an increasing need to decrease noise produced by vehicle air conditioning systems. Decreasing the noise of an air conditioning system may be achieved by reducing an air flow rate of the air conditioning system. Reducing the air flow rate, however, deteriorates the performance of the air conditioning system. There is a necessity for an air conditioning system that achieves high air flow rates and low noise.
To achieve low noise and high air flow rates for an air conditioning system, the most effective way may be enlarging the ventilating area of a heat exchanger (in particular, an evaporator) in the air conditioning system. To enlarge the ventilating area, simply increasing, for example, the width of the evaporator leads to the increase of a widthwise space occupied by the evaporator, to thereby increase the size of the air conditioning unit. This makes it difficult to provide an installation space for the air conditioning system in a vehicle and dose not substantially provide low noise and high air flow rates for the air conditioning system. In the centralized layout, the large evaporator prevents providing a foot space for a driver's seat or a glove box space in front of a passenger's seat.
An object of the present invention is to provide an air conditioning unit and air conditioning system for a vehicle, capable of achieving low noise and high air flow rates and minimizing the outside dimensions of the air conditioning unit.